Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
  • C07D307/77—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom ortho- or peri-condensed with carbocyclic rings or ring systems
  • C07D307/87—Benzo [c] furans; Hydrogenated benzo [c] furans
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K31/00—Medicinal preparations containing organic active ingredients
  • A61K31/33—Heterocyclic compounds
  • A61K31/335—Heterocyclic compounds having oxygen as the only ring hetero atom, e.g. fungichromin
  • A61K31/34—Heterocyclic compounds having oxygen as the only ring hetero atom, e.g. fungichromin having five-membered rings with one oxygen as the only ring hetero atom, e.g. isosorbide
  • A61K31/343—Heterocyclic compounds having oxygen as the only ring hetero atom, e.g. fungichromin having five-membered rings with one oxygen as the only ring hetero atom, e.g. isosorbide condensed with a carbocyclic ring, e.g. coumaran, bufuralol, befunolol, clobenfurol, amiodarone
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P25/00—Drugs for disorders of the nervous system
  • A61P25/24—Antidepressants

Definitions

• the present invention relates to a method for the preparation of the well-known antidepressant drug citalopram, 1 - [3-(dimethylamino)propyl] - 1 -(4-fluorophenyl)- 1 ,3 -dihydro-5 -isobenzofuran- carbonitrile.
• Citalopram is a well-known antidepressant drug that has now been on the market for some years and has the following structure: It is a selective, centrally acting serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitor, accordingly having antidepressant activities.
• the antidepressant activity of the compound has been reported in several publications, eg. J. Hyttel Prog. Neuro-Psychopharmacol. & Biol. Psychiat. 1982, 6, 277-295 and A. Gravem Acta Psychiatr. Scand.1987, 75, 478-486.
• the compound has further been disclosed to show effects in the treatment of dementia and cerebrovascular disorders, EP-A-474580.
• Citalopram was first disclosed in DE 2,657,013, corresponding to US 4,136,193. This patent publication describes the preparation of citalopram by one method and outlines a further method which may be used for preparing citalopram.
• the corresponding l-(4-fluoropheny ⁇ )-l,3-dihydro-5- isobenzofurancarbonitrile is reacted with 3-(N,N-dimethylamino)propyl-chloride in the presence of methylsulfinylmethide as condensing agent.
• the starting material was prepared from the corresponding 5-bromo derivative by reaction with cuprous cyanide.
• citalopram may be manufactured by a novel favourable process via l-(4-fluorophenyl)-l,3-dihydroisobenzofurane-5-formaldehyde prepared by ring closure of 2,4-dihydroxymethyl-l-[l-(4-fluorophenyl)-l-hydroxy-l-methyl]benzene and oxidation of the resulting 5 -hydroxymethyl- 1 -(4-fluorophenyl)- 1 ,3 -duhydroisobenzofuran.
• the present invention thus relates to a method for the preparation of citalopram wherein the aldehyde of formula
• citalopram which is isolated in the form of the base or as a pharmaceutically acceptable acid addition salt thereof.
• the compound of formula (II) is prepared by reduction of a compound of formula to form a compound of formula
• the invention also relates to the intermediate having the formula
• the invention relates to an antidepressant pharmaceutical composition comprising citalopram manufactured by a process of the invention.
• the alkylation is carried out by reaction of a compound of formula (I) with a 3 -(dimethylamino)propylhalogenide as described in US 4, 136, 193.
• the citalopram intermediates having the formulas (I) and (II) may be prepared by the process illustrated in the following reaction scheme:
• the conversion of the compound of formula (111) to a compound of formula (V) may be carried out using conventional techniques.
• the reducing agent used for reduction of the compound of (III) may be LiAlH 4 , NaAlH 2 (OCH 2 CH 2 OMe) 2 , NaBH 4 /BF 3 -Et 2 0, NaBH 4 /I 2 or any another suitable reducing agent
• the ring closure of the compound of formula (IV) may be carried out by dehydration using mineral acids such as H 3 P0 4 , H 2 S0 4 , HC1 or another suitable dehydrating agent or by ring closure of the corresponding active ester in presence of a base as described in EP 347 066.
• the oxidation of the compound of formula (V) may be carried out using Mn0 2 , Ni0 2 , (NH ) 2 Ce(N0 3 ) 6 or another suitable oxidixing agent.
• Conversion of the formaldehyde group of the compound of formula (II) to a cyano group may be carried out by reaction with hydroxylamine followed by treatment with a dehydrating agent such as SOCl 2 .
• a dehydrating agent such as SOCl 2 .
• Other methods are described in WO 99/30548, see in particular page 6.
• the compound of formula (III) may be prepared by oxidation of the corresponding dimethyl compound as described in N.S.Dokunikhin, B.V.Salov, A.S.Glagoleva Zhurnal Obshchei Khimii 1964, 34, 995-998.
• the alkylation of the compound of formula (I) to form citalopram may be performed according to the process of US 4,136,193 or WO 98/019611.
• the alkylation may be carried our as described in co-pending DK application No PA 200000353.
• citalopram is prepared by alkylation of a compound of formula (I) with a compound having the formula
• R is halogen or -0-S0 2 -X wherein X is alkyl, aryl, aralkyl or alkylaryl and R 1 is dimethylamino, -0-S0 2 -X wherein X is alkyl, aryl, aralkyl or alkylaryl, or halogen; provided that R is not halogen when R 1 is dimethylamino, followed by isolation of citalopram where R is dimethylamino, or followed by reaction of the resulting compound of formula
• R 2 is halogen or a group of formula -0-S0 2 -X wherein X is as defined above with dimethylamin or a metal salt thereof; and thereafter isolation of citalopram or a pharmaceutically acceptable acid addition salt thereof.
• the alkylation step where the compound of formula (I) is reacted with a compound of formula (VI) is suitably carried out by treatment of the compound of formula (I) with a base such as for example LDA (lithium diisopropylamine), LiHMDS (lithium hexamethyldisilazane), NaH, NaHMDS (sodium hexamethyldisilazane), or NaOMe in an aprotic organic solvent such as THF (tetrahydrofurane), DMF (dimethylformamide), NMP (N-methylpyrrolidon), ethers such as diethylether, or dioxalane, toluene, benzene, or alkanes and mixtures thereof.
• a base such as for example LDA (lithium diisopropylamine), LiHMDS (lithium hexamethyldisilazane), NaH, NaHMDS (sodium hexamethyldisilazane), or NaOMe in
• the anion formed is then reacted with a compound of formula (VI) whereby a group of formula -CH 2 - CH 2 -CH 2 -R 2 or a group of formula -CH 2 - CH 2 -CH 2 -N(CH 3 ) 2 is introduced into position 1 of the isobenzofuranyl ring system.
• the compound of formula (VII) is then reacted with dimethylamin or a metal salt thereof, such as M + , " N(CH 3 ) 2 wherein M + is Li + or Na + .
• the reaction is suitably carried out in an aprotic organic solvent such as THF (tetrahydrofurane), DMF (dimethylformamide), NMP (N-methyl pyrrolidon), ethers such as diethylether, or dioxalane, toluene, benzene, or alkanes and mixtures thereof.
• reaction conditions, solvents, etc. used for the reactions described above are conventional conditions for such reactions and may easily be determined by a person skilled in the art.
• citalopram may be prepared by:
• Citalopram is on the market as an antidepressant drug in the form of the racemate. However, in the near future the active S-enantiomer of citalopram is also going to be introduced to the market.
• S-citalopram may be prepared by separation of the optically active isomers by chromatography.
• alkyl refers to a branched or unbranched alkyl group having from one to six carbon atoms inclusive, such as methyl, ethyl, 1-propyl, 2-propyl, 1- butyl, 2-butyl, 2-methyl-2-propyl, 2,2-dimethyl- 1 -ethyl and 2-methyl- 1 -propyl.
• aryl refers to a mono- or bicyclic carbocyclic aromatic group, such as phenyl and naphthyl, in particular phenyl.
• aralkyl refers to aryl-alkyl, wherein aryl and alkyl is as defined above.
• Halogen means chloro, bromo or iodo.
• Citalopram may be used as the free base or as a pharmaceutically acceptable acid addition salt thereof.
• acid addition salts such salts formed with organic or inorganic acids may be used.
• organic salts are those with maleic, fumaric, benzoic, ascorbic, succinic, oxalic, bismethylenesalicylic, methanesulfonic, ethanedisulfonic, acetic, propionic, tartaric, salicylic, citric, gluconic, lactic, malic, mandelic, cinnamic, citraconic, aspartic, stearic, palmitic, itaconic, glycolic, p-aminobenzoic, glutamic, benzene sulfonic and theophylline acetic acids, as well as the 8- halotheophyllines, for example 8-bromotheophylline.
• inorganic salts are those with hydrochloric, hydrobromic, sulfuric
• the acid addition salts of the compounds may be prepared by methods known in the art.
• the base is reacted with either the calculated amount of acid in a water miscible solvent, such as acetone or ethanol, with subsequent isolation of the salt by concentration and cooling, or with an excess of the acid in a water immiscible solvent, such as ethylether, ethylacetate or dichloromethane, with the salt separating spontaneously.
• a water miscible solvent such as acetone or ethanol
• a water immiscible solvent such as ethylether, ethylacetate or dichloromethane
• compositions of the invention may be administered in any suitable way and in any suitable form, for example orally in the form of tablets, capsules, powders or syrups or parenterally in the form of usual sterile solutions for injection.
• the pharmaceutical formulations of the invention may be prepared by conventional methods in the art.
• tablets may be prepared by mixing the active ingredient with ordinary adjuvants and/or diluents and subsequently compressing the mixture in a conventional tabletting maschine.
• adjuvants or diluents comprise: Corn starch, potato starch, talcum, magnesium stearate, gelatine, lactose, gums, and the like. Any other adjuvant or additive, colourings, aroma, preservatives etc. may be used provided that they are compatible with the active ingredients.
• Solutions for injections may be prepared by solving the active ingredient and possible additives in a part of the solvent for injection, preferably sterile water, adjusting the solution to the desired volume, sterilising the solution and filling it in suitable ampoules or vials.
• Any suitable additive conventionally used in the art may be added, such as tonicity agents, preservatives, antioxidants, etc.
• the invention is further illustrated by the following examples.
• Step 1 2,5-Dihydroxymethyl-l-[l-(4-fluoro-phenyl)-l ⁇ hydroxy-1 -methyl] benzene LiAlH t (15.2 g, 0.6 mole) is covered with toluene (800 rnL). THF (400 mL) is added. 4-Fluorobenzophenone-2',4'-dicarboxylic acid J) (58 g, 0.2 mole) is added in portions of about 10 grams. The temperature is allowed to rise to 50 °C. The mixture is heated at reflux temperature for 114 hour. After cooling to 10 °C, water (100 mL) is added carefully. K 2 C0 3 (150 g) is added and the suspension is stirred for 14 hour.
• Step 2 5-Hydroxymethyl-l-(4-fluorophenyl)-l,3-dihydroisobenzofurane.
• H 3 P0 4 200 mL, 60%
• triol 2,4-dihydroxymethyl-l-[l-(4-fluoro ⁇ henyl)-l-hydroxy-l- methyl] -benzene 50 g
• the mixture is heated to 80 °C for 2 hours.
• the title compound crystallises and is filtered off. Recrystallization from EtOH/water ((1:3), 400 mL). Yield: 44 grams (90%, total for step 1 and 2).
• Mp 101-03 C.
• Step 3 l-(4-Fluorophenyl)-l,3-dihydroisobenzofurane-5-formaldehyde.
• Step 4 l-(4-Fluorophenyl)-l,3-dihydroisobenzofurane- 5-carbonitrile.

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• Health & Medical Sciences (AREA)
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• Organic Chemistry (AREA)
• Medicinal Chemistry (AREA)
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• General Health & Medical Sciences (AREA)
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• Engineering & Computer Science (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Neurosurgery (AREA)
• Biomedical Technology (AREA)
• Bioinformatics & Cheminformatics (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Psychiatry (AREA)
• Pain & Pain Management (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Steroid Compounds (AREA)
• Nitrogen And Oxygen Or Sulfur-Condensed Heterocyclic Ring Systems (AREA)
• Furan Compounds (AREA)

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• 2001
  • 2001-02-19 IE IE20010143A patent/IES20010143A2/en not_active IP Right Cessation
  • 2001-02-21 FR FR0102341A patent/FR2805813A1/fr active Pending
  • 2001-02-21 NL NL1017414A patent/NL1017414C1/nl not_active IP Right Cessation
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  • 2001-02-22 TR TR2002/02048T patent/TR200202048T2/xx unknown
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• 2003
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